In liquid sample analysis, for example, in liquid chromatography, capillary electrophoresis, and blood chemistry analysis, smaller dimensions of capillaries will often result in improved performance characteristics, save time, and result in reduced production and analysis costs. Miniaturized channel or capillary systems provide more effective system design, result in lower overhead due to decreased instrumentation sizing and additionally reduce sample and solvent consumption.
An evolving approach for making capillaries that are useful for chemical analysis is by micromachining. Production of miniaturized separation systems involving fabrication of microstructures in silicon by micromachining or microlithographic techniques has been described. See, e.g. Fan et al., Anal. Chem. 66(1):177-184 (1994); Manz et al., Adv. in Chrom. 33:1-66 (1993); Harrison et al., Sens. Actuators, BB10(2):107-116 (1993); Manz et al., Trends Anal. Chem. 10(5): 144-149 (1991); and Manz et al., Sensors and Actuators B (Chemical) B1(1-6):249-255 (1990). The use of micromachining techniques to fabricate miniaturized separation devices on silicon or borosilicate glass chips can be found, in U.S. Pat. No. 5,194,133 (Clark et al.); U.S. Pat. No. 5,132,012 (Miura et al.); in U.S. Pat. No. 4,908,112 (Pace); and in U.S. Pat. No. 4,891,120 (Sethi et al). Miniaturized columns made in a polyimide material is disclosed in U.S. Pat. No. 5,500,071 by Kaltenbach et al. and in U.S. Pat. No. 5,571,410 by Swedberg et al. However, a need still exists for a technique that can manufacture in a relatively short time a large number of miniaturized channels or columns with well defined lumen.